allow config help in gateway mode (#9356)
allow config help in gateway mode (#9356)

allow `mc admin config set mygateway/ audit_webhook --env`
to fetch the documentation as needed, this is just to
ensure that our users can still access the relevant
ENV docs while running in gateway mode.
harshavardhana/minio,aead/minio,harshavardhana/minio,harshavardhana/minio,aead/minio,balamurugana/minio,fwessels/minio,aead/minio,aead/minio,harshavardhana/minio,aead/minio,fwessels/minio,minio/minio,NitishT/minio,fwessels/minio,fwessels/minio,donatello/minio,aead/minio,vadmeste/minio,harshavardhana/minio,harshavardhana/minio,vadmeste/minio,minio/minio,harshavardhana/minio,NitishT/minio,aead/minio,NitishT/minio,NitishT/minio,balamurugana/minio,aead/minio,donatello/minio,krisis/minio,krisis/minio,harshavardhana/minio